ASTM International Publishes New WVTR Tests for Solid Oral Drug Packs

Test methods were developed by a Product Quality Research
Institute working group after a 10-year program of study.

By Hugh E. Lockhart, PhDProfessor Emeritus, School of Packaging, Michigan State University

ASTM International has published a new test standard for WVTR (Water Vapor Transmission Rate) of solid oral drug packages. The Container Closure Working Group (CCWG) of the Product Quality Research Institute (PQRI) concluded a 10-year program of study of WVTR in solid oral drug packs with publication of the method.

In January 2001, PQRI assigned to the CCWG the task of finding a way to avoid unnecessary stability testing in instances in which moisture permeation is the Critical Quality Attribute and the water uptake of a new package is the same as or better than the existing package.

The Container Closure Working Group has included the following members during the years of research and publication:

James Bergum, Bristol-Myers Squibb

Hugh Lockhart, MSU

Yisheng Chen, Novast Laboratories

Dan Malinowski, Pfizer; group chairman

Rey Chern, Merck

Chris Moreton, FinnBrit Consulting

Ronald Forster, Amgen

Claudia Okeke, USP

Randy Glenn, sanofi-aventis

Dennis O’Reilly, GSK

Rich Hollander, Pfizer

Vicki Penn, PQRI

Desmond Hunt, USP

Susan Zuk, FDA

Don Klein, FDA

The Container-Closure Working Group developed three new methods of test for water vapor transmission of solid oral drug packages. The methods were published by ASTM International in April 2011 as D7709-11e1, Standard Test Methods for Measuring Water Vapor Transmission Rate (WVTR) of Pharmaceutical Bottles and Blisters.

Previous standard methods available did not provide a clear distinction among the high-barrier multiple-layer package forms—the new
standard does. The methods in the current standard minimize variability and allow clear discrimination among barrier packages currently available for pharmaceutical products. There is a method for bottles, another for high barrier blisters, and a third one for low barrier blisters, such as 5 to 10 mil PVC.

The test duration is two days for low barrier blisters, and 35 days for bottles and high barrier blisters at 40°C, 75% RH. The test is in accordance with ICH climatic conditions.

This standard provides a high degree of precision in the results. Between-laboratory test results have yielded
%RSDs as low as 3–5% for WVTRs in the range of 0.1 to 1.0 mg/day-package. These values are typical of coated and laminated barrier blisters currently in use. Bottles tested by these methods displayed WVTR means in the range of 1.0 to 8 mg/day-bottle and RSD of 2–12%.

Because all data are reported as mg/day-package, the standard provides a means for making a direct comparison between bottles (multiple-dose packages) and blisters (single-dose packages) by taking the dose unit into consideration. The user of the method may assign WVTR values according to
the number of doses contained in a stability-tested approved drug package. The WVTR data then become water gain per unit of medication regardless of the number of units in the package.

The CCWG members are confident that data obtained using D7709 can be used to characterize the WVTR properties of packages in which successful stability testing has been done (e.g., packages for FDA-approved drugs on the market). WVTR data for alternative packages can then be compared with the approved package to reduce the length of time and amount of resources required for choosing and testing alternative packaging for approved drugs.

PQRI was formed in the late 1990s by agreement among several member organizations. At this time, the current member organizations include: the American Association of Pharmaceutical Scientists (AAPS), the Consumer Healthcare Products Association (CHPA), the United States Pharmacopeia (USP), the U.S. Food and Drug Administration (FDA), Health Canada (HC), and the International Pharmaceutical Excipients Council of the Americas (IPEC - Americas).

The standard is based on WVTR research conducted by the CCWG during the years 2001 to 2010. The research reports are available at the CCWG’s page on the PQRI Web site, www.pqri.org[5].

The CCWG worked as a task group of ASTM subcommittee D10.32 while writing the standard. The standard is available from ASTM International for $39. It can be obtained from ASTM at www.astm.org/Standards/D7709htm[6].

The working group urges all interested parties to obtain the standard and apply it to their evaluation of solid oral drug packages. Those who want further participation in application of this standard and development of other standards can join ASTM subcommittee D10.32 on Consumer, Pharmaceutical, and Medical Packaging.
To learn more, contact Diane Trinsey at dtrinsey@astm.org[7]. 